A police officer for the Massachusetts Institute of Technology (MIT) has been shot and killed at the campus outside Boston, authorities said early Friday. As the manhunt began for the shooter, police reportedly became involved in a chase with several suspects in which explosives went off and gunshots rang out.

Live news reports said police officers were dealing with explosives left on the ground after the chase in the Watertown area, just west of Cambridge where MIT is located and eight miles to the west of central Boston. Police were told to switch off mobile phones and other electronic devices for fear of setting off explosives.

Police converged on a Watertown neighbourhood where there were reports of explosives being detonated and police also told reporters to turn off their phones.

Dozens of officers and National Guard members arrived and television outlets report that gunfire and explosions had been heard. A helicopter was circling overhead.

Authorities early on Friday were calling for somebody to get on the ground and put their hands up and a loud thud was heard after someone shouted "fire in the hole".

Reporters were being told to move away from the scene. A police officer told a reporter: "If you want to live turn off your cellphone."

It was not clear whether the MIT and Watertown incidents were connected. MIT is in Cambridge to the north-west of the Boston city centre, and Watertown is further to the west of that.

The police officer at MIT had been responding to report of a disturbance Thursday night when he was shot multiple times, according to a statement from the Middlesex district attorney and Cambridge police. It said there were no other victims.

MIT said on its website that police were sweeping the campus in Cambridge and urged people to remain indoors until further notice. People were urged to stay away from the Stata Building, a mixed-use building with faculty offices, classrooms and a common area.

The drama comes little more than three days after the twin bombing of the Boston Marathon that killed three people, wounded more than 180 others and led to an increase in security across the city.

The campus shooting took place about 10.30pm local time outside an MIT building, according to state police spokesman Dave Procopio.

The officer, who was not immediately identified, was taken to a hospital where he was pronounced dead from his wounds.